The question whether the notion of rigidity can be extended in a fruitful way beyond singular terms has received a standard answer in the literature, according to which non‐singular terms designate kinds, properties or other abstract singular objects, and generalized rigidity is the same thing as singular term rigidity, but for terms designating such objects. I offer some new criticisms of this view and go on to defend an alternative view, on which non‐singular terms designate extensions in general, and generalized rigidity is identity of extension across possible worlds. I develop some fundamental positive considerations that make this view virtually inevitable as a view of generalized rigidity, emphasizing its exclusive ability to offer a purely logical justification of the necessity of several kinds of statements that go beyond true identity statements between rigid singular terms.

中文翻译：

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刚性和必要的应用


刚性概念是否可以以富有成效的方式扩展到单数术语之外的问题已经在文献中得到了标准答案，根据该答案，非单数术语指定种类、属性或其他抽象的单数对象，而广义刚性是同一回事作为单数术语“刚性”，但用于指定此类对象的术语。我对这种观点提出了一些新的批评，并继续捍卫另一种观点，即非奇异术语一般指代扩展，而广义刚性是跨可能世界的扩展的同一性。我提出了一些基本的积极考虑，使这种观点实际上不可避免地成为一种普遍僵化的观点，强调其独特的能力，为几种超越严格单数术语之间的真实同一性陈述的陈述的必要性提供纯粹的逻辑论证。